Please help with margin of error

Question

 

I don't need the answer for #1 I got that one correct, but please help me with #2 and #3 thank you in advance

 

#1 .You conduct a survey and find that 422 students out of 813 would vote for Hillary Clinton, if they could vote (same numbers as other problem). What is the margin of error for your survey? Give your answer as a whole percent. Remember to include your % sign. Ans 4%

 

#2 You are conducting a survey and you want to keep your margin of error to 4%. How many participants should you have in your sample?(whole number)

 

#3 You conduct a survey and find that 422 students out of 813 would vote for Hillary Clinton (same numbers as other problem). What is the likely range for the population proportion? Give your answer as a whole percent, then a dash (-), then another whole percent. Remember to include your % signs.

Answer 1

Use the formula you used in the first question.  Rearrange it to solve for n.  Think about rounding...

 

 

422/813- error to 422/813 + error